The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Wireless telecommunication systems require accurate control of transmit power under a wide range of operating conditions. This includes “3G” systems that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications and “4G” systems such as Long Term Evolution (LTE) and Mobile WiMax. Accurate and robust transmit power control is required both in user equipment (UE) such as cellular phone, tablets, computers and mobile hotspots and in service provider equipment such as base stations, eNodeBs, and Wireless Access Points (WAP).
Transmit power control can generally be characterized as either open loop power control (OLPC) or closed loop power control (CLPC). OLPC adjusts the output power based on predetermined calibration data. However, under OLPC, it is difficult to compensate for variations in the characteristics of the transmitter due to part-to-part variations in the components of the transmitter. Similarly, it is also difficult to compensate for changes in the characteristics of the transmitter over time as parts age or under all operating conditions.
CLPC differs from OLPC by using power measurement feedback, which allows CLPC to be potentially more accurate than OLPC.